You should calculate if there is any edging or ditches to trim. If what you said on the original post is all the yard has I would give and estimate of $50-60 dollars. But you are right it does kinda depend on what mower you are using and if you are working by yourself. If you feel that the customer is kinda clueless on lawn management pricing go ahead and charge $70-80. If it will be cut once a week make the price a little lower that if you are gonna cut every 10 days or 14days.

I wouldn't go near an acre for less than $80, I don't care if they had a 35,000 sq ft mansion on it, it would still be at LEAST $80.
That way I could hire Lawn Choupique to cut it for me and still amke a profit .....

$80 per hour? I would not know what to do will all that money. You know, it has allways amazed me how from time to time I will read how will some old person dies who never made over minimun wage in their life will leave a million dollars in their will to the local college or some other charity. Yet someone making $80 per hour only has time to complain. Surly at $80 per hour you are a millionair many times over.

Well, I wasn't complaining, just stating a fact, afterall, my expenses considering insurance, license, certification, etc., etc., are a bit more than I am sure you are paying, plus the cost of equipment and repairs ... oops, sorry, I forgot, you don't have any of those and your "crapsman" never breaks down ... so I guess for the two hours or more it would take you to cut, trim, edge, and blow that property with your 21" mower, I guess you would be runnin' home to mama with that whole $35 you made and think you had found gold "in them thar hills".